This proposal is to request support for a Keystone meeting entitled "Drugs Against Protozoan Parasites: Target Selection, Structural Biology and Medicinal Chemistry", which will be held in Copper Mountain from April 9 - April 13, 2005. The meeting will address important issues in parasite drug development. Hundreds of millions of people worldwide suffer from diseases caused by protozoan parasites. Effective drugs are lacking for sleeping sickness and leishmaniasis, and current therapies for treating malaria are at risk due to drug resistance. Thus, the development of new lines of anti-protozoan agents is urgently needed. With the sequencing of genomes of organisms responsible for malaria, sleeping sickness, and leishmaniasis, this is an exciting time for the discovery and evaluation of new drug targets, especially when combined with structural biology, combinatorial chemistry, and parasite genetics. Groups of talks, given by chemists, structural biologists, and parasitologists, will exemplify the power of multi-disciplinary collaborations. Experts in drug development outside of parasitology have also been invited in an effort to stimulate their interests in tropical medicine and to learn from their experiences.